badbadmonkey - 11:08 am on May 22, 2012 (gmt 0)
Captchas are utterly useless nowadays. What you see on some forms just beggars belief. Do these web designers even test them out themselves? It's no exaggeration to say that some of them are just impossible, even for a normally sighted person, to pass. And even on the easy ones, the ambiguity of case (z or Z etc) makes them ridiculous.
If it's a special purpose website, in a niche market, it's easy to to come up with challenge questions that the average Russian hacker won't know the answers to even if they look at it manually. I think this is very positive, because it adds a fun challenge to the process. People always like a chance to prove their knowledge.
The problem is that these questions, and particularly the obvious generic "color of coal" variants, will become machine-solvable in time. In much the same way that OCR has progressed in effectiveness. Unfortunately, anything your web visitor can do, a machine can do... it's just an arms race.